Pushbuttons: I'm not 100% sure, but it could be that they're simply not back-lit if the current OPS mode doesn't support them (for instance, orbital DAP selection pushbuttons are only meaningful in OPS 201 and 202), and that they're specifically lit to indicate what mode is active.
So a distinction between 'you can push this button now' and 'you have pushed this button now'
Again, this needs to be checked against the manual.
I've just spent an hour trying to convince JSBSim to implement a pulsed mode for the RCS - in this mode, whenever the stick is moved out of neutral a fixed-duration pulse is fired. So the elevator command is non-zero, generate a property that is set to unity for a configurable time duration. Seems JSBSim dosn't fancy discontinuities - I've now needed a series of five tags to do it for one channel... Sample-hold the internal timer whenever stick is moved out of neutral, compare difference between held timer and current timer with the desired duration, flick a switch between 0 and 1 based on that value, flick a second switch to make the property -1, 0 or 1 dependent on stick position and multiply the two. I haven't found a more graceful way of doing it - we do have <delay> tags, but they expect numerical input, that makes them non-configurable unfortunately...